Growth modelling as a tool to support nature-based solution for natural hazard protection

Soil and Water Bioengineering methods for natural hazard control, slope stabilization and river regulation processes are widely used and a viable alternative to common civil engineering techniques as part of nature-based solutions (NbS). The knowledge on the effects of different design schemes and the dynamic development of vegetation regarding is mostly handled through expert knowledge and a comprehensive approach for the design regarding the performance and management phase is still not fully implemented in the application of the diverse techniques. Therefore, this study aims to create a concept for a vegetation model to predict the development on pioneer stands and as a further consequence the performance of used techniques. The further goal includes the development of a conceptual basis for a vegetation growth model for NbS, which emphasizes on the spatial and temporal level of the modelling process and the calculation of the main vegetation parameters height, diameter and crown width. The concept is tested on three different study sites with pioneer stands of Robinia pseudoacacia (Black Locust) in Lower Austria to generate control results for the further adaptation of the model concept. Applied vegetation growth models (forest models, succession models and gap-models) are used for the conceptualization and verified for the requirements of NbS specific techniques. The development of a flowchart provides an overview of the elaborated framework and requirements for the ecological and biological parameters regarding the time and space criteria of a NbS model. The main result is the development of an adequate competition modelling that can depict the dynamic suppression mechanisms within pioneer vegetation stands and is capable for further development. The first 10-year simulation run with a yearly interval serves initially as a medium-term prediction and provides an insight into the further adjustment of the establishment module and review of the competition module. The results show the need in NbS with regard to long-term monitoring, data generation and the uniform documentation of the solutions.